This is the process that water goes through before it arrives in your glass. If we follow the route taken by a single drop of water, you'll soon see that this is a long journey, and one with many potential pitfalls along the way.
Stage 1: Our drop of water is drawn from a lake, a spring, a river or an underground water table. This is called Abstraction.
Stage 2: To begin with, this drop of water must pass through a simple mesh to remove the largest solid debris. It is then filtered through a series of progressively finer filters. These processes are referred to as Screening and Fine Screening.
Stage 3: A flocculent is then added to the water. This process causes any remaining solids to fall as flocs to the bottom of a huge settling tank. These steps are called Flocculation and Decantation.
Stage 4: Our drop of water must now face another test. It must find its way through a bed of fine sand, whose job is to remove particles so small that they are invisible to the naked eye. This is Sand filtration.
Stage 5: Our journey is still far from over! Our drop of water is now disinfected using a gas - Ozone - which will kill any bacteria and viruses it contains. This stage is called Ozonization.
Stage 6: Now, it has to pass through particles of activated carbon, which retains the very smallest particles, such as pesticides. This is the Activated Carbon Filtration phase.
Stage 7: Chlorine is now added to prevent bacteria from growing in the water as it passes through the supply pipes. This is Chlorination.
Stage 8: Our drop of water is now approaching the end of its journey, stored in high-level reservoirs or water supply tanks. From here, it will travel through the frost-protected underground pipeline network and into your tap.
So the next time you pour yourself a glass of water, take a shower or clean your teeth, remember this little drop of water and its very long journey!